Exogenous Ketosis Improves Sleep Efficiency and Counteracts the Decline in REM Sleep Following Strenuous Exercise

Available evidence indicates that ketone bodies may improve sleep quality. Therefore, we determined whether ketone ester (KE) intake could counteract sleep disruptions induced by strenuous exercise. Ten well-trained cyclists with good sleep quality participated in a randomised crossover design consisting of two experimental sessions each involving a morning endurance training and an evening high-intensity interval training ending one hour before sleep, after which polysomnography was performed overnight. Post-exercise and 30 min before sleeping time, subjects received either 25 g KE (EXKE) or a placebo drink (EXCON). A third session without exercise, but with placebo supplements (RCON) was added to evaluate the effect of exercise per se on sleep. Blood D-β-hydroxybutyrate concentrations transiently increased to ~3 mM post-exercise and during the first part of the night in EXKE but not in EXCON or RCON. Exercise significantly reduced REM sleep by 26% (p = 0.001 vs. RCON) and increased wakefulness after sleep onset (WASO) by 95% (p = 0.004 vs. RCON). Interestingly, KE improved sleep efficiency by 3% (p = 0.040 vs. EXCON) and counteracted the exercise-induced decrease in REM sleep (p = 0.011 vs. EXCON) and the increase in WASO (p = 0.009 vs. EXCON). This was accompanied by a KE-induced increase in dopamine excretion (p = 0.033 vs. EXCON), which plays a pivotal role in sleep regulation. In addition, exercise increased sleep spindle density by 36% (p = 0.005 vs. RCON) suggesting an effect on neural plasticity processes during sleep. These data indicate that KE ingestion improves sleep efficiency and quality following high-intensity exercise. We provide preliminary evidence that this might result from KE-induced increases in dopamine signalling.